Insufficient shoulder external rotation increases shoulder injury, surgery in pitchers

The likelihood of shoulder injury and shoulder surgery was increased when professional baseball players had insufficient shoulder external rotation on the throwing side, according to study results.

“In the past, clinicians and people dealing with individuals with shoulder injuries related to baseball and overhead sports have often looked at the loss of internal rotation, commonly referred to as GIRD [glenohumeral internal rotation deficit], as a reason for shoulder injuries and this paper portrays it as the complete opposite: do not worry so much about the loss of internal rotation, but the loss of external rotation seems to correlate more so with injuries,” Kevin E. Wilk, PT, DPT, FAPTA, associate clinical director at Champion Sports Medicine in Birmingham, Ala., told Orthopedics Today.

Passive range of motion

Wilk and his colleagues assessed passive range of motion of the glenohumeral joint during spring training among 296 professional pitchers between 2005 and 2012. Overall, 505 examinations were performed, with researchers recording passive range of motion data for external and internal rotation in 288 pitchers. Researchers also measured external and internal rotation, as well as forward shoulder flexion, in 287 pitchers.

After initial passive range of motion examination, 17% of pitchers had 75 shoulder injuries that placed them on the disabled list. Overall, 7% of the pitchers on the disabled list required surgery.

Kevin E. Wilk, PT, DPT, FAPTA
Kevin E. Wilk

Compared with the non-throwing shoulder, results showed pitchers had less internal rotation, total rotation and flexion, but they had more external rotation in their throwing shoulder. Researchers found 18% of 288 pitchers had glenohumeral internal rotation deficit, of which 12% were placed on the disabled list and 4% required surgery. Total rotation deficit was found in 46% of 288 pitchers. Of these, 21% were placed on the disabled list and 8% underwent surgery, according to study results.

Among 287 pitchers with forward flexion measurements, flexion deficit was found in 18%. Researchers found 12% of pitchers with a flexion deficit were placed on the disabled list and 6% required shoulder surgery. Insufficient external rotation was noted in 46% of 288 pitchers. Results showed pitchers with insufficient external rotation were 2.2-times more likely to be placed on the disabled list, as well as 4-times more likely with undergo shoulder surgery when compared to pitchers without insufficient external rotation.

“What we found was … [that] external rotation was actually protective to the shoulder and we were surprised that we did not find association with the loss of internal rotation or the loss of cross-body motion,” Wilk said.

Future research

Wilk said these are not absolute findings and more research is needed on the topic that should span across gender, teams and levels of sport.

“This is a group of individuals on one particular team over an 8-year period. It would be interesting to look at this with either other teams or other levels, such as college, high school players or even recreational athletes,” Wilk said. “We may find completely different findings in the female softball player in college vs. the recreational male baseball player, as well, and it may also vary based on skill level. These are all professional [players] so the question is are there individuals at lesser skill levels that maybe will not have these adaptations.” – by Casey Tingle

Disclosure: Wilk reports no relevant financial disclosures.

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